A number of clinical trials have been conducted in patients with ALS. These have demonstrated promise and more are likely as more effective treatments are developed. These trials have used a variety of endpoints to assess response, including manual motor testing scores (MMT) and maximal voluntary isometric contraction megascores (MVIC). Which of these has the best interobserver reliability and which is the most valid marker of disease progression in ALS is uncertain. A major untested variable is the reproducibility of tests between different centers in multi-center trials. We will assess test reliability by comparing MMT and MVIC scores between institutions and individuals, and test validity by comparing rate of change beween MMT and MVIC to the ALSFRS patient survey which has been previously validated. Each institution of the Great Lakes ALS association will enroll patients with ALS. For each patient MMT, MVIC, ALSFRS, PFTs and patient survival will be assessed repeatedly at 3 month intervals for 12 months by two separate examining teams from different institutions. This study will determine which test has the best reproducibility between centers and which is the best marker of diseas progression. These features ilwl be critical in planning future multi-center therapeutic trials.